Operations involving the handling and processing of fluids entail fluids being contained in various types of fluid chambers. As used herein, the term fluid refers to any process material that is of a sufficiently flowable nature and may include, but is not limited to, a liquid, a gas, a gas/liquid mixture, a liquid/solid mixture or a gas/solid mixture. These fluid chambers may take the form of pipes, conduits, tubes, or open channels for transporting fluids under the influence of gravity or of pumping systems, or they may take the form of vessels, tanks, or vats for carrying out various chemical or other processes. Monitoring process variables within a fluid chamber is a key component of overall process assessment and control, and such assessment and control may require injection and/or extraction of materials to or from the chamber. While access ports for measurement and control may be designed within a fluid chamber initially, such is not always the case. The introduction of continuous processing methods often requires the need to monitor process and product conditions in-line using various types of sensors.
There are numerous challenges to designing access devices for fluid chambers, particularly for industries processing food, drinks, pharmaceuticals, and bio-products, for example. Industry standards require the design to conform to specific criteria in order to be approved for sanitary applications. Such, access devices should be designed to maintain hygienic conditions in the area where the access device penetrates the fluid chamber. Maintenance of hygienic conditions is promoted by not having crevices or voids where process products may collect and stagnate creating biological risks.
In addition to the hygienic risk from product entrapment in voids during normal processing, such voids can also entrap products during draining procedures, and form pockets or voids that collect gases during filling and startup procedures. This is particularly true for highly viscous fluids that do not easily drain by gravity and require substantial pressure to create steady flow through the process.
Accordingly, the access device should be robust and designed such that both the device and a seal that is used to seal the device to the fluid chamber can be securely held in place without the pressure within the chamber compromising the integrity of the connection. Additionally, the design of a hygienic process connection has to be simple and capable of being easily disassembled for inspection and cleaning purposes.
There are known devices that are designed for gaining access to fluid chambers used for processing/conveying fluids under hygienic requirements. FIGS. 1 and 2, for example, illustrate a conventional method for inserting a sensor into a hygienic processing pipeline. Such devices are provided with an elastomeric seal 104 for forming a sealed relationship between the access device 101 and the edge of an opening 103 in the fluid chamber 102. The design of these connection assemblies is generally that, when installed, the seal 104 lies between the wall of the chamber 102 and the access device 101 to be inserted in the chamber. When the access device 101 is installed, a clamping ring 105 compresses the seal 104 axially between the surface of the chamber 103 and the access device 101.
The geometry of the access device in the vicinity of the chamber opening where the seal is located can introduce localized zones of fluid stagnation 106 within the chamber. These zones can have a negative hygienic impact on the fluid contained within the chamber since they cannot be effectively cleaned in situ by routine Clean-In-Place (CIP) procedures. This often results in the need to dismantle the support structure and access device in order to carry out manual cleaning procedures on the dismantled components at frequent intervals. These procedures are both labor intensive and time consuming.
Another disadvantage of this kind of access device installation geometry is the restriction it places on the choice of installation location within the process. For example, the non-vertical orientation of the access device 101 can result in incomplete fluid drainage on shutdown procedures, and create voids or pockets that can trap gases during filling and startup procedures. Both can result in product contamination and waste. Further, restricting the angular orientation of the access device 101 in an attempt to reduce the fluid drainage problems invariably worsens the gas entrapment problem.
A further problem encountered by the known forms of access device 101 is that an increase in the fluid pressure within the chamber will have a tendency to move the access device 101 away from the seal 104 and the chamber opening 103 resulting in a reduction in the compression of the seal 104. This produces an increased hygienic risk from fluid ingress into the seal 104 contact areas, as well as leakage of the product out of the chamber.